Boris Johnson’s idea of a bridge spanning the English Channel has split opinion but is technically possible, experts have said.

Dr Kostas Tsavdaridis, associate professor in Structural Engineering at the University of Leeds, said constructing such a bridge was “doable” so long as issues including waves, water flow and depth, wind strength and soil condition were properly planned for first.

However issues including the weather, shipping and the financial implications could make the concept a less-than-practical reality.

It is thought that a bridge could be challenging for vessels crossing one of the busiest shipping channels in the world, sometimes with limited visibility.

Dr Tsavdaridis said he would use such a bridge “but only on the good days of the year”, as conditions could be harsh.

He said any seismic action in the area would not have a significant effect on the structure, and it was being mooted for the narrowest and shallowest stretch of the channel.

At 20-plus miles, it would be one of the longest bridges, but “it has been done in the past”, he said.

The world’s longest bridge is the Danyang–Kunshan Grand Bridge in China, which spans just over 100 miles.

Graphic originally issued in 1985 showing the four contenders bidding to build the cross-Channel link from Britain to France (PA)

He said: “If you are asking me just as an engineer I will say: Yes, it’s something that can be done, provided that very meticulous investigations take place.

“All that is doable. The problem, it comes usually from the economic and financial perspective – whether it is worth it to go for something like this.”

Expert estimates put the cost of such a project at more than £100 billion, according to the Times.

Alan Dunlop, who teaches architecture at the University of Liverpool, told the paper: “I’d say at least £120 billion for a Channel bridge and that’s a conservative estimate.